Faster bugreports (1/n)

Adds a thread pool to dumpstate.

Bug: 136262402
Test: atest dumpstate_test
Change-Id: I83b48a696c60fafbd4cb0dd62d3acceaa43caabb
Merged-In: I83b48a696c60fafbd4cb0dd62d3acceaa43caabb
(cherry picked from commit 3432b93ad0e423a3bdd0b87fe3f3dabb9d572dae)
diff --git a/cmds/dumpstate/DumpPool.cpp b/cmds/dumpstate/DumpPool.cpp
new file mode 100644
index 0000000..7324ead
--- /dev/null
+++ b/cmds/dumpstate/DumpPool.cpp
@@ -0,0 +1,171 @@
+/*
+ * Copyright (C) 2020 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "dumpstate"
+
+#include "DumpPool.h"
+
+#include <array>
+#include <thread>
+
+#include <log/log.h>
+
+#include "dumpstate.h"
+#include "DumpstateInternal.h"
+#include "DumpstateUtil.h"
+
+namespace android {
+namespace os {
+namespace dumpstate {
+
+const std::string DumpPool::PREFIX_TMPFILE_NAME = "dump-tmp.";
+
+DumpPool::DumpPool(const std::string& tmp_root) : tmp_root_(tmp_root), shutdown_(false) {
+    assert(!tmp_root.empty());
+    deleteTempFiles(tmp_root_);
+}
+
+DumpPool::~DumpPool() {
+    shutdown();
+}
+
+void DumpPool::start(int thread_counts) {
+    assert(thread_counts > 0);
+    assert(threads_.empty());
+    if (thread_counts > MAX_THREAD_COUNT) {
+        thread_counts = MAX_THREAD_COUNT;
+    }
+    MYLOGI("Start thread pool:%d", thread_counts);
+    shutdown_ = false;
+    for (int i = 0; i < thread_counts; i++) {
+        threads_.emplace_back(std::thread([=]() {
+            setThreadName(pthread_self(), i + 1);
+            loop();
+        }));
+    }
+}
+
+void DumpPool::shutdown() {
+    std::unique_lock lock(lock_);
+    if (shutdown_ || threads_.empty()) {
+        return;
+    }
+    while (!tasks_.empty()) tasks_.pop();
+    futures_map_.clear();
+
+    shutdown_ = true;
+    condition_variable_.notify_all();
+    lock.unlock();
+
+    for (auto& thread : threads_) {
+        thread.join();
+    }
+    threads_.clear();
+    deleteTempFiles(tmp_root_);
+    MYLOGI("shutdown thread pool");
+}
+
+void DumpPool::waitForTask(const std::string& task_name, const std::string& title,
+        int out_fd) {
+    DurationReporter duration_reporter("Wait for " + task_name, true);
+    auto iterator = futures_map_.find(task_name);
+    if (iterator == futures_map_.end()) {
+        MYLOGW("Task %s does not exist", task_name.c_str());
+        return;
+    }
+    Future future = iterator->second;
+    futures_map_.erase(iterator);
+
+    std::string result = future.get();
+    if (result.empty()) {
+        return;
+    }
+    DumpFileToFd(out_fd, title, result);
+    if (unlink(result.c_str())) {
+        MYLOGE("Failed to unlink (%s): %s\n", result.c_str(), strerror(errno));
+    }
+}
+
+std::unique_ptr<DumpPool::TmpFile> DumpPool::createTempFile() {
+    auto tmp_file_ptr = std::make_unique<TmpFile>();
+    std::string file_name_format = "%s/" + PREFIX_TMPFILE_NAME + "XXXXXX";
+    snprintf(tmp_file_ptr->path, sizeof(tmp_file_ptr->path), file_name_format.c_str(),
+             tmp_root_.c_str());
+    tmp_file_ptr->fd.reset(TEMP_FAILURE_RETRY(
+            mkostemp(tmp_file_ptr->path, O_CLOEXEC)));
+    if (tmp_file_ptr->fd.get() == -1) {
+        MYLOGE("open(%s, %s)\n", tmp_file_ptr->path, strerror(errno));
+        tmp_file_ptr = nullptr;
+        return tmp_file_ptr;
+    }
+    return tmp_file_ptr;
+}
+
+void DumpPool::deleteTempFiles(const std::string& folder) {
+    std::unique_ptr<DIR, decltype(&closedir)> dir_ptr(opendir(folder.c_str()),
+            &closedir);
+    if (!dir_ptr) {
+        MYLOGE("Failed to opendir (%s): %s\n", folder.c_str(), strerror(errno));
+        return;
+    }
+    int dir_fd = dirfd(dir_ptr.get());
+    if (dir_fd < 0) {
+        MYLOGE("Failed to get fd of dir (%s): %s\n", folder.c_str(),
+               strerror(errno));
+        return;
+    }
+
+    struct dirent* de;
+    while ((de = readdir(dir_ptr.get()))) {
+        if (de->d_type != DT_REG) {
+            continue;
+        }
+        std::string file_name(de->d_name);
+        if (file_name.find(PREFIX_TMPFILE_NAME) != 0) {
+            continue;
+        }
+        if (unlinkat(dir_fd, file_name.c_str(), 0)) {
+            MYLOGE("Failed to unlink (%s): %s\n", file_name.c_str(),
+                   strerror(errno));
+        }
+    }
+}
+
+void DumpPool::setThreadName(const pthread_t thread, int id) {
+    std::array<char, 15> name;
+    snprintf(name.data(), name.size(), "dumpstate_%d", id);
+    pthread_setname_np(thread, name.data());
+}
+
+void DumpPool::loop() {
+    std::unique_lock lock(lock_);
+    while (!shutdown_) {
+        if (tasks_.empty()) {
+            condition_variable_.wait(lock);
+            continue;
+        } else {
+            std::packaged_task<std::string()> task = std::move(tasks_.front());
+            tasks_.pop();
+            lock.unlock();
+            std::invoke(task);
+            lock.lock();
+        }
+    }
+}
+
+}  // namespace dumpstate
+}  // namespace os
+}  // namespace android